From b2d60e4a17364cd0d4fa6cad7fa7ff4415ab4e69 Mon Sep 17 00:00:00 2001
From: Reyk Floeter <reyk@cvs.openbsd.org>
Date: Wed, 25 Jun 2008 15:32:19 +0000
Subject: this diff changes the bootloader to skip the CHS sanity check if LBA
 (EDD) is found and OK. it will also fix chainloading into OpenBSD from grub
 in a few scenarios where grub doesn't report the CHS correctly but the LBA.
 and we don't need CHS if there is LBA.

this has been in the snapshots for a while.

with input from weingart@
ok deraadt@
---
 sys/arch/amd64/stand/libsa/biosdev.c | 25 +++++++++++++++----------
 sys/arch/i386/stand/libsa/biosdev.c  | 25 +++++++++++++++----------
 2 files changed, 30 insertions(+), 20 deletions(-)

diff --git a/sys/arch/amd64/stand/libsa/biosdev.c b/sys/arch/amd64/stand/libsa/biosdev.c
index 0e4439c8296..7358eab09f6 100644
--- a/sys/arch/amd64/stand/libsa/biosdev.c
+++ b/sys/arch/amd64/stand/libsa/biosdev.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: biosdev.c,v 1.5 2008/06/25 15:26:44 reyk Exp $	*/
+/*	$OpenBSD: biosdev.c,v 1.6 2008/06/25 15:32:18 reyk Exp $	*/
 
 /*
  * Copyright (c) 1996 Michael Shalayeff
@@ -124,14 +124,6 @@ bios_getdiskinfo(int dev, bios_diskinfo_t *pdi)
 	pdi->bios_cylinders &= 0x3ff;
 	pdi->bios_cylinders++;
 
-	/* Sanity check */
-	if (!pdi->bios_cylinders || !pdi->bios_heads || !pdi->bios_sectors)
-		return(1);
-
-	/* CD-ROMs sometimes return heads == 1 */
-	if (pdi->bios_heads < 2)
-		return(1);
-
 	/* NOTE:
 	 * This currently hangs/reboots some machines
 	 * The IBM ThinkPad 750ED for one.
@@ -173,6 +165,18 @@ bios_getdiskinfo(int dev, bios_diskinfo_t *pdi)
 	} else
 		pdi->bios_edd = -1;
 
+	/* Skip sanity check for CHS options in EDD mode. */
+	if (pdi->bios_edd != -1)
+		return 0;
+
+	/* Sanity check */
+	if (!pdi->bios_cylinders || !pdi->bios_heads || !pdi->bios_sectors)
+		return(1);
+
+	/* CD-ROMs sometimes return heads == 1 */
+	if (pdi->bios_heads < 2)
+		return(1);
+
 	return(0);
 }
 
@@ -410,7 +414,8 @@ bios_getdisklabel(bios_diskinfo_t *bd, struct disklabel *label)
 	int n = 8;
 
 	/* Sanity check */
-	if(bd->bios_heads == 0 || bd->bios_sectors == 0)
+	if (bd->bios_edd == -1 &&
+	    (bd->bios_heads == 0 || bd->bios_sectors == 0))
 		return("failed to read disklabel");
 
 	/* MBR is a harddisk thing */
diff --git a/sys/arch/i386/stand/libsa/biosdev.c b/sys/arch/i386/stand/libsa/biosdev.c
index 9603fcb8ddd..2b8220225ac 100644
--- a/sys/arch/i386/stand/libsa/biosdev.c
+++ b/sys/arch/i386/stand/libsa/biosdev.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: biosdev.c,v 1.73 2008/06/25 15:26:44 reyk Exp $	*/
+/*	$OpenBSD: biosdev.c,v 1.74 2008/06/25 15:32:18 reyk Exp $	*/
 
 /*
  * Copyright (c) 1996 Michael Shalayeff
@@ -127,14 +127,6 @@ bios_getdiskinfo(int dev, bios_diskinfo_t *pdi)
 	pdi->bios_cylinders &= 0x3ff;
 	pdi->bios_cylinders++;
 
-	/* Sanity check */
-	if (!pdi->bios_cylinders || !pdi->bios_heads || !pdi->bios_sectors)
-		return 1;
-
-	/* CD-ROMs sometimes return heads == 1 */
-	if (pdi->bios_heads < 2)
-		return 1;
-
 	/* NOTE:
 	 * This currently hangs/reboots some machines
 	 * The IBM ThinkPad 750ED for one.
@@ -176,6 +168,18 @@ bios_getdiskinfo(int dev, bios_diskinfo_t *pdi)
 	} else
 		pdi->bios_edd = -1;
 
+	/* Skip sanity check for CHS options in EDD mode. */
+	if (pdi->bios_edd != -1)
+		return 0;
+
+	/* Sanity check */
+	if (!pdi->bios_cylinders || !pdi->bios_heads || !pdi->bios_sectors)
+		return 1;
+
+	/* CD-ROMs sometimes return heads == 1 */
+	if (pdi->bios_heads < 2)
+		return 1;
+
 	return 0;
 }
 
@@ -413,7 +417,8 @@ bios_getdisklabel(bios_diskinfo_t *bd, struct disklabel *label)
 	int n = 8;
 
 	/* Sanity check */
-	if (bd->bios_heads == 0 || bd->bios_sectors == 0)
+	if (bd->bios_edd == -1 &&
+	    (bd->bios_heads == 0 || bd->bios_sectors == 0))
 		return "failed to read disklabel";
 
 	/* MBR is a harddisk thing */
-- 
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